Answer:
The correct option is C.
Step-by-step explanation:
Given that Carlos operates a helicopter. Carlos decides to measure the rotational velocity of the helicopter blades. we have to find the appropriate unit for Carlos's purpose.
The angular velocity ω is the rate of change of angle with respect to time,
The formula to find the rotational velocity is

Angle measure in radians or degrees and time in second.
Hence, the appropriate unit for Carlos's purpose is degrees per second.
The correct option is C.